System Development Life Cycle (SDLC)Six Phases of the System Development Life CycleSlide 3SDLC PhasesPhase 1: Preliminary InvestigationPhase 2: System AnalysisPhase 2: System Analysis Tools UsedPhase 2: System Analysis Documentation ProducedPhase 3: System DesignPhase 3: System Design Tools UsedPhase 3: System Design Documentation ProducedPhase 4: System DevelopmentPhase 5: System ImplementationPhase 5: System Implementation Types of ConversionPhase 5: System ImplementationPhase 6: Operations & MaintenanceSlide 17Deliverables of the SDLCSystem DevelopmentLife Cycle (SDLC)CS208Six Phases of the System Development Life CyclePreliminary Investigation Assesses feasibility and practicality of system System Analysis Study old system and identify new requirementsDefines system from user's viewSystem Design Design new/alternative systemDefines system from technical viewSix Phases of the System Development Life CycleSystem DevelopmentNew hardware and software is acquired, developed, and testedSystem ImplementationSystem installation and trainingSystem Operation & Maintenance Daily operationPeriodic evaluation and updatingSDLC Phases Preliminary Investigation System Operation & Maintenance System Analysis SystemImplementationn System Design System DevelopmentPhase 1: Preliminary InvestigationDetermine if a new system is neededThree primary tasks:Define the problemBy observation and interview, determine what information is needed by whom, when, where and whySuggest alternative solutionsPrepare a short reportIn depth study of the existing system to determine what the new system should do.Expand on data gathered in Phase 1In addition to observation and interviews, examine:Formal lines of authority (org chart)Standard operating procedures How information flowsReasons for any inefficienciesPhase 2: System AnalysisPhase 2: System Analysis Tools UsedChecklists - list of questionsTop-down analysis - start with top level components, break down into smaller parts through each successive levelGrid charts - to show relationship between inputs and outputsSystem flowcharts - charts flow of input data, processing, and output which show system elements and interactionsPhase 2: System Analysis Documentation ProducedComplete description of current system and its problemsRequirements for for new system including:SubjectScopeObjectivesBenefitsPossible development schedulePhase 3: System DesignUses specifications from the systems analysis to design alternative systemsEvaluate alternatives based upon:Economic feasibility - Do benefits justify costs?Technical feasibility - Is reliable technology and training available?Operational feasibility - Will the managers and users support it?Phase 3: System DesignTools UsedComputer-Aided Software Engineering (CASE) tools are software-based products designed to help automate the production of information systems. Examples:Diagramming ToolsData RepositoriesPrototyping ToolsTest Data GeneratorsDocumentation ToolsProject Management ToolsPhase 3: System DesignDocumentation ProducedSystem Design ReportDescribe Alternatives including:Inputs/OutputsProcessingStorage and BackupRecommend Top Alternative based upon:System Fit into the OrganizationFlexibility for the futureCosts vs. benefitsPhase 4: System DevelopmentBuild the system to the design specifications Develop the softwarePurchase off-the-shelf software ORWrite custom softwareAcquire the hardwareTest the new system Module (unit) test - tests each part of systemIntegration testing - tests system as one unitCreate manuals for users and operatorsPhase 5: System ImplementationConvert from old system to new systemTrain usersCompile final documentationEvaluate the new systemPhase 5: System ImplementationTypes of ConversionDirect/plunge/crash approach – entire new system completely replaces entire old system, in one stepParallel approach - both systems are operated side by side until the new system proves itselfPilot approach - launched new system for only one group within the business -- once new system is operating smoothly, implementation goes company-widePhased/incremental approach - individual parts of new system are gradually phased-in over time, using either crash or parallel for each piece.Phase 5: System ImplementationUser TrainingEase into system, make them comfortable, and gain their supportMost commonly overlooked Can be commenced before equipment deliveryOutside trainers sometimes usedPhase 6: Operations & MaintenanceTypes of changes:Physical repair of the systemCorrection of new bugs found (corrective)System adjustments to environmental changesAdjustments for users’ changing needs (adaptive)Changes to user better techniques when they become available (perfective)Phase 6: Operations & MaintenanceEvaluation MethodsSystems audit - performance compared to original specificationsPeriodic evaluation - “checkups” from time to time, modifications if necessaryDeliverables of the SDLC Begin buildingnew system System convertedUsers trainedCoded and Tested System Design Specifications Preliminary Investigation System Analysis SystemDesign System Implementation System Development SystemMaintenance Approved Feasibility Study Operational System Documentation completed Abort Project Goto next phase Goto Previous phase
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